Electrical ignition gas torch



May 26, 195,9 E. D. wlLsoN ELECTRICAL IGNITION GAS TORCH 2 Sheetsl-Sheet1 Filed March l0, 1952 May 26, 1959 l E. D. WILSON ELECTRICAL IGNITION@As TORCH 2 Sheets-Sheet 2 Filed March l0, 1952 United States Patent Thepresent invention relates to blowpipe type gas torches of the type usedfor soldering, brazing or welding and having built-in igniter means.

In my prior Patents Nos. 2,232,893, issued February 25, 1941, and2,477,917, issued August 2, 1949, are disclosed gas torches havingbuilt-in igniter means, the ignition mechanism including relativelymovable ilint and striker steel elements. The torches disclosed in myaforementioned patents have been widely adopted and have enjoyedconsiderable commercial success. It is a primary object of the presentinvention to provide certain improvements in gas torches and moreparticularly with respect to the ignition means incorporated therein.

More speciiically, it is an object of the present invention to provide anew and improved self-contained electrically igniting blowpipe type gastorch.

A still further object of the present invention is to provide a new andimproved torch of the class described including a hollow handle withinwhich is incorporated an electrical power supply connected to anignition electrode disposed inside of the arne tip for igniting the gasflowing therethrough.

Another object of the present invention is to provide a new and improvedtorch of the class described having electrical power supply meansprovided in the handle thereof and a single manual control leverextending externally of the handle operatively connected to a valvecontrolling the flow of gas to the burning tip and to the electricalpower supply means in such a manner that when the lever is depressed forusing the torch, the gas valve is opened and an arc is produced at anignition electrode arranged within the flame tube adjacent its outer endfor igniting the gas. v

A further object is to provide a new and improved ignition electrodearrangement for a torch of the class described.

Another object of the invention is to provide a new and improvedremovable flame tube for a torch of the class described.

In accordance with the illustrated embodiment, the torch includes ahandle having a passage for inflammable gas therethrough and having aflame tube mounted on one end of the handle in communication with thepas,- sage, a valve being provided in the handle for controlling the owof gas through the passage. An electrical power supply means is providedwithin the handle which is connected to an ignition electrode arrangedin the outer end of the flame tube. A manual control lever is providedon the outer surface of the handle which is operatively connected to thecontrol valve and also to the electrical power supply means so that whenthe lever is depressed as for using the torch, the valve is first openedto permit gas to ilow through the flame tube and immediately thereafter,an electrical arc is produced at the ignition electrode for igniting thegas.

Further objects and advantages of the present invention will be apparentfrom a perusal of the following description taken in connection with theaccompanying draw- ICC ings wherein like numerals refer to like partsthroughout, while the features of novelty will be pointed out withgreater particularity in the appended claims.

In the drawings,

Fig. 1 is a longitudinal elevation illustrating a gas torch of thepresent invention constructed in accordance with one modificationthereof;

Fig. 2 is a longitudinal view through the torch shown in Fig. 1 with thecasing and certain other parts shown in section to better illustrateinternal details;

Fig. 3 is a longitudinal view taken through the torch, with certainparts broken away, or shown in section, but at right angles to the viewshown in Fig. 2 and generally in the direction indicated by the arrow3-3 of Fig. 2;

Fig. 4 is an enlarged sectional view through the flame tip shown in Fig.l and illustrating more particularly the electrode arrangement providedin the end of the llame tube;

Fig. 5 is a sectional view drawn to an enlarged scale and taken alongthe line 5--5 of Fig. 4;

Fig. 6 is a schematic wiring diagram illustrating the electricalconnection arrangement of the various elements provided within thetorch;

Figs. 7, 8 and`9 are detail views illustrating the switch mechanismincorporated in the torch and shown in various successive positionsduring normal operation thereof; and

Fig. l0 is a fragmentary view, partly in section, illustrating a portionof the torch constructed in accordance with a rfurther modification ofthe invention.

Referring now to the drawing and particularly to Fig. 1, the blowpipe ortorch of the present invention is comprised of a hollow handle dened inpart by a cylindrical tube 10 preferably of insulating material such as,for example, horn ber, the tube 10 being secured to a head portion 11 bymeans of screws 12. Secured to the end of the head portion 11 andextending outwardly therefrom is a ame tube 13 having a removable tip 14threadedly secured to the outer end thereof, the opposite end of theflame tube 13 being anchored to the bushing 15 which, in turn, isremovably secured to the head 11 in a manner to be described more fullyhereinafter.

Referring now to Figs. 2 and 3, which illustrate the cylindrical tube 10in longitudinal cross-section so as more clearly to illustrate theinternal arrangement of the various parts as mounted within the handle,a passage for inflammable gas is provided therethrough in the form of atube 20, the outer end of which is an- ,chored within the end of a hosefitting 21 through which connection may be made to a source ofinflammable gas supply through a exible hose (not shown). The tting 21extends through a cooperating opening provided through the removablemetal end cap or disc 22 and is insulated therefrom by a collar andbushing of insulating material indicated .at 23. The end cap 22 isremovably secured in place in .an abutting relation against the end ofthe tube 10 by means of a knurled nut 24 cooperatively and threadedlyarranged about the base of the fitting 21. The opposite end of themetallic tube 20 is secured to the head member 11 in communication witha passage 25 which in turn communicates with a valve well 26 extendingin the direction transversely of the longitudinal axis of the handle.Arranged within the well 26 is a suitable valve element 27 which` may,for example, be an ordinaryautomobile tire valve element, the valveelement being shown in this instance threaded into a sleeve/28 which isarrangedwith a tight press .t within the intermediate portion of thewell 26. Arranged Within the enlarged outer end portion ofthe well 26 isa cylindrical rubber bushing 29 having` an opening therethrough somewhatlarger in diameter than the valve stem. Arranged within the outer end ofthe bushing 29 assaoee is a round headed stud 3) having a stemprojecting inwardly of the bushing, the inner end of the stem beingnormally slightly spaced away from the adjacent end of the valve stem.Communicating with the outer end of the valve well is a passage 31 whichextends diagonally inwardly toward the axis of the handle and opens intoa bore 32 provided for the cooperative reception of the inner end of theburner assembly unit.

The burner unit will now be described, which includes the bushing 15,the liame tube 13 and the tip 14 previously mentioned. The bushing is ofcylindrical coniiguration and is fitted cooperatively into an axial boreof corresponding diameter provided in the end of the head member 11. Forretaining the burner unit in position and for preventing accidentaldislodgment of the burner unit from the handle, a friction dog 35 ismounted within a slot provided in the head member 11 and is retainedtherewithin by means of a transverse pin 36 shown more clearly in Fig,3. The dog 35 is resiliently biased in the clockwise direction as viewedin Fig. 3 by means of a small spring 37 provided for that purposebetween the head member 11 and a lip of the dog projecting inwardly ofthe bore provided in the head member. One side of the bushing 15 isprovided with a groove 3S extending in the longitudinal direction whichis adapted cooperatively to receive the inwardly projecting lip of thedog 35. The depth of the groove 38 is such that as the bush ing 15 isinserted into the cooperating bore in the head member, the lip of thedog 35 engages with the bottom of the groove 38 and the dog 35 isrotated about the pivot pin 36 in the counterclockwise direction againstthe bias of spring 37. With the disposition of the lip frictionallyengaging the bottom of groove 38 relative to the position of the pivotpin 36, as shown, accidental withdrawal of the bushing 15 from thehandle is prevented. By manually pressing against the portion of the dogprojecting from the outer surface of the head member 11, the lockingaction of the dog lip against the bushing 15 may be broken whereupon theburner unit may readily be separated from the handle.

Threaded coaxially into the end of the bushing 15 is a jet element 41 ofcylindrical configuration and of such a diameter as to fit relativelysnugly into the cylindrical recess 32. In order to effect asubstantially gas-tight seal therebetween, a rubber ring 42 is mountedwithin an an nular groove provided about the element 41. A small disc ofvery line wire mesh material 44 is secured within an enlarged outer endportion of the axial bore provided through the jet element 41 defining aash arrester. This screen also serves as a lter for the inammable gas toprevent clogging of the fine jet opening 45 provided in the opposite endof the jet element 41. Air for mixing with the gas emerging from the jetorilice 45 is drawn through a pair of passages 46 and 47 provided in thebushing 15. The flame tube 13 is suitably secured such as by brazing inthe outer end of the bore 48 in the bushing 15 and extends axiallyoutwardly therefrom. The details of construction of the tip 14 Will bedescribed in connection with the ignition system.

In accordance with the present invention, any suitable self-containedsource of electrical potential may be provided within the hollow handleof the torch capable of producing a high voltage arc discharge at anignition electrode arranged within the burner tip and for igniting theinflammable gas owing therethrough. Suitable selfcontained sources forelectrical potential may be either of the magneto-electric type or ofthe battery type. In this instance, a high voltage generating means isprovided in the handle including a low voltage battery, a high tensioncoil, a condenser and a control switch connected in a conventionalmanner. As shown in the drawings, Fig. 3, a pair of small vest-pocketsize flashlight batteries 51 and 52 is .provided within the outer end ofthe tubular handle member 10 immediately adjacent the removable end cap22, the batteries being arranged in a lll side-by-side relation butfacing in opposite directions whereby the metallic end cap 22 in and ofitself serves to make electrical connection between the unlike polarityend terminals of the batteries held in a firm contacting relationagainst the end cap. The batteries are maintained in a proper positionwithin the handle by means of a block 53 of insulating material ofcylindrical outer configuration and having a transverse slot 54 providedtherethrough of a width so as cooperatively to receive the batteries 51and 52. Mounted in the bottom of the slot 54 are helical contact-makingsprings 55 and 56 which engage and make electrical contact with thebattery terminals opposite the end cap 22. Arranged adjacent the block53 is a high tension coil 57 having one terminal thereof connected tothe contact spring 56, another terminal connected to the ignitionelectrode through the conductor 58 and a third terminal connected to theswitch mechanism through conductor 59. The battery Contact spring 55 isconnected through conductor 61 to ground, such as to the switch frame asindicated at 62.

Neglecting, for the moment, the details of the switch mechanism, theelectrode structure arranged within the tip and llame tube together withthe electrical connection arrangement thereof to the conductor 58 willnow be described. As previously mentioned, the burner element isremovably attached to the handle and, accordingly, provision must bemade for effecting an insulated electrical contact between the conductor58 and an electrical conductor 65 which extends through the hollow ametube 13. As shown in the view of Fig. 3 which illustrates the torch headmember 11 in cross section, it will be observed that conductor 5S iselectrically connected to one end of a helical compression spring 66mounted within a surrounding tubular member 67 of insulating material.The opposite end of the spring 66 bears against the head of a contactpin 68 longitudinally slidable within the tubular member 67, which pinis biased outwardly of the handle. The end of the conductor 65 issecurely anchored in the bushing 15 and insulated therefrom by a sleeve69 of insulating material, the conductor 65 being provided with acontact 7@ at the end thereof adapted to be engaged by the end of thepin 63 as the bushing 15 is attached to the head member 11.

Referring now more particularly to the enlarged detail views of Figs. 4and 5, it will be observed that the other end of the conductor 65 ismounted within a metal bushing '71 which, in turn, is secured with apress lit into the outer end of the tube 13. The metal bushing 71 isprovided with a plurality of grooves 72 extending longitudinally thereofthroughout its full extent, which deline passages for inflammable gasiiowing through the tube 13 and serves as a back-tire arrester. It is tobe understood that the conductor 65 extending through the tube 13 isinsulated. The end of the conductor extends through a cooperatingopening provided in the center of the bushing 71 and is insulatedtherefrom either by means of a separate sleeve of insulating material orby a continuation of the insulation provided about the remainder of theconductor. The end of the conductor 65 projects a very slight distancefrom the forward end of the bushing 71 and defines an ignition electrode74. As previously indicated, the electrode portion of the conductor 65is secured in any suitable manner to the bushing 71 and preferably issecured thereto before the bushing 71 is inserted into the end of thetube 13. Upon insertion of the bushing 71 into the end of the tube 13the surplus length of the conductor 65 will cause it to buckle somewhatas indicated in Fig. 4 which will cause the conductor to exert a certainamount of pressure in the outward direction thereby tending to offsetany tendency which the conductor might otherwise experience to crawlback into the tube 13 and thus pull the electrode end out of the bushing'71.

Threaded upon the exterior end portion of the tube 13 is a flame tip 76having an axial opening .77 extending therethrough, the inner endportion' of the opening 77 flaring outwardly to the outer diameter ofthe tube 13 and dening an ignition chamber 78 surrounding the electrode74. Inasmuch as the bushing 71 is grounded to the tube 13 by reason ofthe press lit mounting therewithin, the bushing and the ignitionelectrode 74 define a spark gap means between which arcing will occurupon application of ignition potential to the ignition electrode 74.

Referring now to the views of Figs. 2 and 3, the details of the switchdevice will be described. The switch device includes a U-shaped metalframe member 81, one end ange of which is suitably secured to atransversely extending disc 80 of insulating material tting snuglywithin the surrounding tube 10, the opposite parallel llange portion ofthe frame being suitably secured to the inner transverse surface of thetorch head member 11. The conductor 59 is electrically secured to a stud82 securely fastened to and extending through the switch frame member 81and insulated therefrom by means of a bushing 83 of insulating material,the opposite end of the stud 82 being electrically connected to thecontact member 84. A cooperating contact is provided upon a small leafspring member 85 which is secured to the adjacent flange of the framemember. A second small leaf spring 86 extends parallel with the leafspring contact bearing member 85 in slightly spaced relation therefrom,the outer end of the leaf spring 86 being doubled back upon itself asindicated at 87 overlying the extreme outerv end of the leaf spring 85as illustrated more clearly in the views of Figs. 7, 8 and 9. It is tobe understood that the leaf spring 85 is so biased as normally to urgeits contact into closed circuit relationship with respect to the contactmounted on the member 84. The second leaf spring 86, however, isoppositely biased land being slightly stronger than the spring 85normally holds the contacts apart or in the open circuit condition.

Mounted for free rotation upon the frame 81 is a wheel 89 which isbiased to a particular position by means of a spring 90, one end of thespring being secured to the frame 81, the opposite end of the spring 90normally resting upon the attened side 95 of `a hub portion of wheel 89.A pair of pins 91 are provided on the Wheel 89 projecting outwardlytherefrom on opposite sides of the flattened hub portion 95 for purposesto be hereinafter described. i The normal or rest position of the wheel89 with the end of the spring 90 resting against the llattened side 95of the wheel hub is shown in the enlarged detail view of Fig. 7.Projecting outwardly from the front side, or to the right as viewed inFig. 3, is a further pair of pins 92 and 93. The pin 92 is arranged forcooperative engagement by a trigger element 94 while the pin 93 isadapted to engage with the underneath side of the leaf spring 86, asviewed in Figs. 7, 8 and 9, as will be more fully described.

Referring more particularly to the views of Figs. 1 and 2, manualoperating means for simultaneously opening the valve 27 for permittingthe ilow of inflammable gas to the burning tip and for causing arcing atthe electrode is provided in the form of a pivoted lever 101. This leveris U-shaped in cross section and projects outwardly through an elongatedslot provided in a cap piece 102. One end of the cap 102 is hooked intoa slot provided in the tube as indicated at 103, while the forward endof the cap is fastened to the head member 11 by means of screw 104. TheIforward end of the lever 101 is bifurcated, the bifurcated end portions105 being hooked under the thread of a T-shaped screw 106 which isthreaded into the head member 11. The lower edges of the bifurcatedportions 105 of the lever 101 are adapted to engage against the head ofthe button 30 and upon depression of the lever 101 against the handle,the button 30 will be pushed inwardly to compress the rubber bushing 29while the stem ofl the button 30 engages against the stem of the valveto force the latter to the open position. Upon release of the lever, theresiliency of the rubber bushing 29 Will force the head 30 vand thelever outwardly to the normal valve closed condition illustrated in Fig.2. For effecting adjustment of the lever 101, the T-headed screw 106 maybe screwed either inwardly or outwardly, thereby changing the pivotalpoint for the lever 101 relative to the surface of the button 30.Pivotally mounted between the parallel side walls of the U-shaped lever101 is the trigger element 94 mounted upon the pin 111 and normallybiased in the clockwise direction as viewed in Fig. 2, by means of asmall spring 112 operatively connected between the trigger element andthe lever member 101. The inner end portion 114 of the trigger element94 projects through a slot 115 in the tubular casing 10. The inner endportion 114 of the trigger element normally assumes a position of restin engagement with the pin 92 on wheel 89. As the lever 101 is pressedinwardly toward the handle, the wheel 89 is rotated in the clockwisedirection as shown more clearly in Fig. 8. As the lever 101 reaches itsinner limit of travel, the shoulder 117 provided on the trigger element94 engages against the outer surface of the tubular casing 10 at the endof the slot 115 causing the trigger element to rotate in thecounterclockwise direction about its pivotal supporting pin 111 andagainst the bias of spring 112, and thereby causes the outer end portionof the trigger part 114 to slip oif the pin 92 on the switch wheel 89.In the view of Fig. 8, the pin 92 is shown just about to slip off theend of the trigger portion 114. As soon as this occurs, and due to thebiasing effort of the spring 90 bearing against the flattened wheel hub95, the wheel 89 is suddenly released for rotation in thecounterclockwise direction as indicated by the arrow on the wheel inFig. 9, whereupon the pin 93 strikes against the underneath surface ofthe spring 86 to propel the same upwardly because of the inertia of thewheel 89. The upward movement of the spring 86 permits the contact tomove upwardly into engagement with the contact 84 to close the circuitfrom the battery through the high tension coil 57. The spring isselected so as to have sucient strength to supply suicient inertia tothe wheel 89 to cause the same to move the spring 86 upwardly intoengagement with the contact 85 as shown inv Fig. 9, whereupon thecounterclockwise rotation of the wheel will be stopped and the action ofthe spring 90 against the flattened hub surface 95 will cause the wheelto reverse direction and ultimately come to its rest position as shownin Fig. 7. The foregoing action causes or permits the contacts 84, 85 toremain closed for a momentary dwell period, starting at the instant thecontact 85rst touches the contact 84 and continuing through the intervalduring which the spring 86 is moved upwardly relative to the contact 85and into engagement therewith and thereafter downwardly as the wheel 90returns to rest position, whereupon the doubled end 87 of the spring 86engages the contact 85 and returns it to the normally open position ofthe switch as shown in Fig. 7. This dwellperiod of switch closure is forthe purpose of eifecting magnetization of the core of the highv tensioncoil 57. Upon reopening of the contacts,' the flux field of the hightension coil 57 is caused suddenly to collapse while the inertia currentilows into the condenser 99 connected in any suitable manner across theswitch contacts, which condenser immediately thereafter again dischargesto produce an arc between the electrode 74 and the bushing 71 previouslydescribed. The arrangement of the trigger 94 and the wheel 89 serves asan escapement linkage connection whereby the switch kis closed andautomatically reopened each time the lever 101 is pressed down. The pins91 adjacent the opposite sides of the flattened surface of the wheel hubare adapted to engage the spring 90 and serve as emergency stops toprevent rotation of the Wheel 89 beyond the point where the spring 90would l lose contact with the surface 95.

The wiring diagram for the various electrical elements incorporated inthe torch is shown in Fig. 6 with reference numerals applied theretocorresponding to reference numerals as applied to the correspondingparts in the other views of the drawings. lt is not believed necessaryto describe further the operation of the circuit inasmuch as it willreadily be recognized by one skilled in the art as a more or lessconventional battery operated ignition circuit. The significant featureof the circuit is that the switch contacts are normally opened and hencethere is no current drain upon the batteries when the torch is eitherlying idle or in use. Power is drawn therefrom only during the briefinterval of time that the contacts of the switch mechanism are closed byactuation of the escapement linkage connection of the switch operatinglever 101. Thus the batteries, even though small in size, willnevertheless serve effectively over a long period of time but mayreadily be replaced when completely worn out. Access to the batterycompartment may be had by removing the nut 24 and the end cap 22.

t will be noted that switch frame 81, high tension coil 57 and dry cellmounting block 53 are all attached to the head member 11. Thisconstruction permits the tube 10 to be withdrawn by sliding the sameaxially and rearwardly relative to the head member, after removingscrews 12, lever cover plate 1&2 and the end plate 22, so as to exposethe switch and other parts for maintenance of the same.

In Fig. l is illustrated a further modification of the invention whichincorporates a safety valve in the torch head to prevent accidentalignition of the gas when the burner unit is removed from the handle. Inthe modification as previously described, it will be understood that ifthe operating lever 101 were depressed when the flame tube or burnerunit 13 is removed from the head 1i, the valve 27 would be openedpermitting inarnmable gas to tlow through the passage 31. into therecess 32. An arc might also occur between the conductor e3 and theadjacent side wall of the head 11, which arc would ignite the gasesiowing from the recess 32. In the modification illustrated in Fig. l0, asafety valve is provided in the recess 32, comprising a valve plug 120biased outwardly of the recess by means of a spring i221 arrangedbetween the bottom of the recess and the plug. The plug i230 is providedwith an enlarged annular ange 122 around its inner end and which isadapted to t against a rubber O-ring 123 arranged within a cooperatingannular recess provided in the side wall of the recess 32 adjacent itsouter end. The jet element 124 secured to the bushing l is similar tothe jet element 41 as previously described, with minor exceptions. Itwill be recalled that the jet clement 41 was provided with a rubberO-ring i2 mounted within a cooperating annular groove for effectingsealing engagement with the smooth cylindrical side wall of the recess32. The jet element 124 in this instance is provided with a smoothcylindrical outer wall which, upon insertion of the bushing into thecooperating recess provided in the head 11, projects into the recess 32,depressing the valve plug 120 and effecting a sealing engagement withthe G-ring E23. The end of the jet clement 124 is transversely groovedas indicated at 1.25 to permit the gas flowing past the valve plug lange122 to pass into the central passage provided through the jet element.

1t will thus be seen that according to the present modification.whenever the burner unit comprising the name tube 13 and bushing i5 isremoved from the torch head 11, the valve 128 will automatically closeso as to prevent the passage of gas from the torch in the event that thelever 101 should be pressed.

Having described the invention in what is considered to be a preferredembodiment thereof, it is desired that it be understood that thespecific details shown and described are merely illustrative and thatthe invention may be carried out in other ways. I claim as my inventionall such modifications as come Within the true spirit and scope of theappended claims.

I claim:

l. In a gas torch including a handle, means defining a passage forinammable gas ,through the handle, a burner unit mounted on said handlein communication with said passage, means in said burner unit defining aspark gap for igniting gas flowing therethrough, a source of electricalpotential in said handle, said source including battery, coil andcondenser devices, circuit means including a switch connecting saiddevices to said spark gap means for causing ignition sparking thereat,said switch comprising a pair of relatively movable contacts, a circularinertia element mounted for rotation [about its axis, resilient meansbiasing said inertia element to a rest position, a lever on said handle,and means including an escapement linkage for connecting said lever tosaid inertia element to rotate said inertia element against the bias ofsaid resilient means in one direction and thereafter to release saidinertia element whereby said resilient means causes said inertia elementto rotate in the opposite direction to eiiect closing of said Contactelements, closing of said Contact elements permitting energization ofsaid coil and subsequent opening of said contacts causing sparking atsaid gap,

2. In a gas torch including a handle, a passage for intiammable gasthrough the handle, a burner unit mounted on said handle incommunication with said passage, means in said burner unit defining aspark gap for igniting gas flowing therethrough, a-source of electricalpotential including a battery, a coil, and a condenser in said handle,and circuit means connecting said source to said spark gap means forcausing ignition sparking thereat, said circuit means including a switchcomprising a pair of relatively movable Contact elements normally biasedout of contact with one another, an inertia wheel operatively associatedwith said switch and having a rest position, spring means biasing saidwheel to said rest position, said inertia wheel adapted upon rotation ina given irection from said rest position to engage said switch and movethe same into contact, a lever on said handle, pawl means operativelyassociated with said lever for momentarily engaging said wheel uponoperation of said lever and eecting rotation of said wheel in thedirection opposite said given direction and then releasing the samewhereby said spring means causes said wheel to rotate in said givendirection to cause closure of said switch contact elements whereuponsaid coil is energized from said battery and arcing caused across saidspark gap upon reopening of said switch contact elements.

3. In an electrically igniting blowpipe having a handle and a burnerunit mounted on one end of said handle, a spark gap means in said burnerunit for producing an igniting spark, high voltage generating means insaid handle connected to said spark gap means for producing a sparkthereat, said high voltage generating means including a high tensioncoil, a battery for charging the same, and switch means for connectingsaid battery to sm'd high tension coil comprising a rst contact and asecond contact, spring means operatively connected with said secondcontact for normally biasing the same out of en- `tagement with said rstcontact, an operating ever, and inertia means responsive to operation ofsaid lever for causing said second contact to move into engagement withsaid rst contact and to remain in engagement therewith for 1a sufficientdwell period to effect magnetization of the core of said coil,whereafter arcing is caused at said spark gap.

4. A blowpipe having a hollow handle and a burner unit mounted on oneend thereof, said burner unit having n spark gap means for producing anigniting spark, high voltage generating means mounted in said handleconnected to said spark gap means for producing a spark thereat, saidhigh voltage generating means including a high tension coil, a batteryfor charging the same, and

closed condition for a suicient dwell period to elect 5 magnetization ofthe core of said coil, thereafter permitting said contacts to open tocause arcing at said spark gap means.

References Cited in the file of this patent UNITED STATES PATENTS985,159 Goodyear Feb. 28, 1911 10 Schwimmer May 27, 1930 Eastman May 15,1934 Fausek et al Aug. 23, 1938 Young Jan. 17, 1939 Smith Feb. 1l, 1941Clark May 6, 1941 Peterson Sept. 27, 1949 See May 13, 1952 Faulkner Oct.20, 1953 Peterson Jan. 19, 1954 Piros et al. Feb. 9, 1954 Sparks May 31,1955

